Speaking to X Factor's digital correspondent Dan Levy in a video on the official website, the former American Idol winner suggested that the contestants should "find what is unique" about them to ensure they stand out.

Clarkson said: "You have to bring something different to the table. I think everybody sometimes just wants to be famous or do what another artist is doing and it's like, 'We already have that artist. Why are you doing that?' Find what is unique about you."

She went on to say that artists should also "enjoy themselves" with the process and make sure they are believable in their performances, saying she can tell when somebody is singing about a broken heart but haven't gone through that in their own life.

"I hate watching people and being like, 'You are not believable. I don't believe you've ever had your heart ripped out'. The believability factor isn't there."

She added: "I sing songs that I have lived or I write them because I have lived them. I think the believability factor is key."

Watch Kelly Clarkson talking to Dan Levy below:

As for whether she had been nervous at appearing in front of Simon Cowell and Paula Abdul, who judged her back on American Idol, she said she had been more nervous about performing 'What Doesn't Kill Me (Stronger)' for the first time.

She added: "[Simon] was always nice to me. So was Paula, so I have very nice memories!"